American author Seanan McGuire has been shortlisted a record-breaking five times for this year's Hugo awards, America's most prestigious science fiction prize.

Writing under her pseudonym Mira Grant, McGuire was shortlisted for the best novel Hugo for Blackout, the finale to her zombie trilogy, and for the best novella prize for San Diego 2014: The Last Stand of the California Browncoats – another story set in her zombie world in which the walking dead attack a comic book convention. As McGuire, she was shortlisted – twice – for the best novelette award, for the self-published In Sea-Salt Tears, about the daughter of two selkies, and for Rat-Catcher, the story of a young prince of cats set in 1666 London, as well as for the best fancast.

"So here are my firsts for this year: First woman to appear on the ballot four times in fiction categories alone. First person to appear on the ballot five times in a single year. First person to appear on the ballot with a purely self-published work."

The author said she had "eaten nothing but ice cream today", and had "cried a lot" after learning of her nominations. "I am grateful and honoured and terrified and fragile and amazed, because this ballot represents the best of 2012 in a very concrete way. I see so many works there that blew my mind, and I look forward to experiencing the rest. Thank you so much. I will try very hard not to let you down."

McGuire will be competing with big names for the best novel Hugo: former winners Kim Stanley Robinson and Lois McMaster Bujold are also shortlisted, Robinson for 2312, set 300 years in the future, and Bujold for Captain Vorpatril's Alliance, part of her acclaimed Vorkosigan saga.

The best novel shortlist is completed with the bestselling John Scalzi's Redshirts, set on the starship Intrepid, and Saladin Ahmed's debut Throne of the Crescent Moon, a fantasy which takes place in a Middle Eastern-style kingdom.

The best novel Hugo, which has been running for more than 50 years, has been won in the past by Ursula K Le Guin, Arthur C Clarke and Isaac Asimov. Winners are decided by votes from members of the World Science Fiction Society, with this year's to be announced on 1 September in San Antonio, Texas.